The value of the bias parameter f00 is added to the concentration value:
NEW CONC = OLD CONC + f00.
7.5 Configuring prism wash
In some applications the process flow does not keep the prism clean because of sticky
process medium or low flow velocity. In these applications the prism can be automatically
cleaned by installing a wash system.
The prism wash settings for sensors A and B are independent of each other. The wash
system is active if a relay has been configured to be a wash relay, see Configuring relays
(page 66), and the wash time is not zero. An automatic wash function can be configured so
that both sensors have dierent parameters.
More information
‣
Prism wash systems (page 39)
7.5.1
Wash cycle
Figure 42 (page 79) shows the wash logic as a flow diagram. The automatic prism wash
cycle described below consists of three phases: precondition, wash and recovery. The
optional preconditioning function is used to, for example, blow out the condensate before
washing. After the preconditioning there is a one-second pause to avoid having both
precondition and wash relays active at the same time.
The wash cycle is initiated when the wash interval has elapsed. The wash can also be started
by closing an external switch, see Configuring input switches (page 68), or manually from
the user interface at the Sensor status display, see Testing prism wash (page 51). The order
of priority for these wash triggers is as follows:
1. Manual wash
2. Remote wash request
3. Wash interval timer
WASH
RECOVERY
INTERVAL
PRECOND.
Figure 41 Automatic prism wash cycle
Chapter 7 – Configuration and calibration
77
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